Modern map displays, particularly those used in aircraft for flight planning and monitoring, are capable of displaying a considerable amount of information such as flight planning information and terrain information. The terrain information consists of situational awareness (SA) terrain and terrain cautions and warnings that, among other things, may indicate where the aircraft may potentially impact terrain. The flight planning information consists of flight path information, altitude information and other information useful to a pilot or crewmember in following and anticipating the path and altitude of the aircraft over the ground.
Three dimensional perspective representations of terrain or out-of-window displays provide better spatial understanding and situation awareness and therefore reduce the navigational workload for a flight crew. These displays are particularly effective at presenting impending danger in the tactical range. In particular, when a 3D terrain representation is used, it aids the flight crew in detecting potential flight path conflicts with terrain as well as planning for optimal paths around potentially hazardous areas in comparison to other display formats (planar or vertical profile only). A flight path display with a terrain underlay will also significantly enhance the perception of depth and relative location during the flight path visualization therefore reducing flight crew work load and improving the vertical awareness relative to terrain, especially when entering flat terrain.
There are significant challenges to producing such displays since such displays frequently must cover a large area of terrain in order to show look-ahead distance compatible with visibility range for typical approach, landing, and take-off phases of flight. Generating the displays in real time with a large amount of terrain data presents significant difficulties for avionics flight management and display systems including the difficulty of performing the enormous computational tasks associated with providing detailed terrain representations over a large area. Generating a display under these circumstances using regular square grids is very computation intensive and leads to visual artifacts. Since on-board avionics systems must be capable of handling multiple outputs (for example, terrain, EGPWS, lateral mapping, weather, etc.) on an integrated display at a sustained frame rate, system throughput must be obtained by reducing as much as possible the computational overhead of each of the tasks.